Evaluation on Anticancer Effect Against HL-60 Cells and Toxicity in vitro and in vivo of the Phenethyl Acetate Isolated from a Marine Bacterium Streptomyces griseus

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    We previously identified Streptomyces griseus as an anti-cancer agent (Kim et al., 2014). In this study, we isolated compounds from S. griseus and evaluated their anticancer effect and toxicity in vitro and in vivo. Preparative centrifugal partition chromatography (CPC) was used to obtain three compounds, cyclo(L-[4-hydroxyprolinyl]-L–leucine], cyclo(L-Phe-trans-4-hydroxy-L-Pro) and phenethyl acetate (PA). We chose PA, which had the highest anticancer activity, as a target compound for further experiments. PA induced the formation of apoptotic bodies, DNA fragmentation, DNA accumulation in G0/G1 phase, and reactive oxygen species (ROS) formation. Furthermore, PA treatment increased Bax/Bcl-xL expression, activated caspase-3, and cleaved poly-ADP-ribose polymerase (PARP) in HL-60 cells. Simultaneous evaluation in vitro and in vivo, revealed that PA exhibited no toxicity in Vero cells and zebrafish embryos. We revealed, for the first time, that PA generates ROS, and that this ROS accumulation induced the Bcl signaling pathway.


    Streptomyces griseus , Marine bacteria , Secondary metabolite , Anti-cancer activity , Toxicity

  • Introduction

    The marine environment is a rich source of natural products with a wide variety of biological activity. During the last three decades, more than 15,000 natural products were isolated from marine organisms (MarinLit, 2008). In many cases, pharmaceutically interesting natural products were isolated from microbes associated with marine invertebrates, rather than the marine invertebrates themselves (Faulkner et al., 2000; Haygood et al., 1997; Proksch et al., 2002; Thoms et al., 2005a; Thoms et al., 2005b). Sponges harbor significant amounts of bacteria in their tissues. In some cases bacteria make up more than 40% of the sponge biomass (Vacelet, 1975; Bewley and Faulkner, 1998). Marine sponge-associated microbes rely on sponges for nutrient acquisition and secondary metabolite production (Hentschel et al., 2002). The various secondary metabolites synthesized by microbial associates also possess excellent bioactivity in many studies (